db/btree/bt_rsearch.c

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996, 1997, 1998
 *  Sleepycat Software.  All rights reserved.
 */
/*
 * Copyright (c) 1990, 1993, 1994, 1995, 1996
 *  Keith Bostic.  All rights reserved.
 */
/*
 * Copyright (c) 1990, 1993
 *  The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *  This product includes software developed by the University of
 *  California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "config.h"

#ifndef lint
static const char sccsid[] = "@(#)bt_rsearch.c  10.21 (Sleepycat) 12/2/98";
#endif /* not lint */

#ifndef NO_SYSTEM_INCLUDES
#include <sys/types.h>
#endif

#include "db_int.h"
#include "db_page.h"
#include "btree.h"

/*
 * __bam_rsearch --
 *  Search a btree for a record number.
 *
 * PUBLIC: int __bam_rsearch __P((DBC *, db_recno_t *, u_int32_t, int, int *));
 */
int
__bam_rsearch(dbc, recnop, flags, stop, exactp)
    DBC *dbc;
    db_recno_t *recnop;
    u_int32_t flags;
    int stop, *exactp;
{
    BINTERNAL *bi;
    CURSOR *cp;
    DB *dbp;
    DB_LOCK lock;
    PAGE *h;
    RINTERNAL *ri;
    db_indx_t indx, top;
    db_pgno_t pg;
    db_recno_t i, recno, total;
    int ret, stack;

    dbp = dbc->dbp;
    cp = dbc->internal;

    BT_STK_CLR(cp);

    /*
     * There are several ways we search a btree tree.  The flags argument
     * specifies if we're acquiring read or write locks and if we are
     * locking pairs of pages.  In addition, if we're adding or deleting
     * an item, we have to lock the entire tree, regardless.  See btree.h
     * for more details.
     *
     * If write-locking pages, we need to know whether or not to acquire a
     * write lock on a page before getting it.  This depends on how deep it
     * is in tree, which we don't know until we acquire the root page.  So,
     * if we need to lock the root page we may have to upgrade it later,
     * because we won't get the correct lock initially.
     *
     * Retrieve the root page.
     */
    pg = PGNO_ROOT;
    stack = LF_ISSET(S_STACK);
    if ((ret = __bam_lget(dbc,
        0, pg, stack ? DB_LOCK_WRITE : DB_LOCK_READ, &lock)) != 0)
        return (ret);
    if ((ret = memp_fget(dbp->mpf, &pg, 0, &h)) != 0) {
        (void)__BT_LPUT(dbc, lock);
        return (ret);
    }

    /*
     * Decide if we need to save this page; if we do, write lock it.
     * We deliberately don't lock-couple on this call.  If the tree
     * is tiny, i.e., one page, and two threads are busily updating
     * the root page, we're almost guaranteed deadlocks galore, as
     * each one gets a read lock and then blocks the other's attempt
     * for a write lock.
     */
    if (!stack &&
        ((LF_ISSET(S_PARENT) && (u_int8_t)(stop + 1) >= h->level) ||
        (LF_ISSET(S_WRITE) && h->level == LEAFLEVEL))) {
        (void)memp_fput(dbp->mpf, h, 0);
        (void)__BT_LPUT(dbc, lock);
        if ((ret = __bam_lget(dbc, 0, pg, DB_LOCK_WRITE, &lock)) != 0)
            return (ret);
        if ((ret = memp_fget(dbp->mpf, &pg, 0, &h)) != 0) {
            (void)__BT_LPUT(dbc, lock);
            return (ret);
        }
        stack = 1;
    }

    /*
     * If appending to the tree, set the record number now -- we have the
     * root page locked.
     *
     * Delete only deletes exact matches, read only returns exact matches.
     * Note, this is different from __bam_search(), which returns non-exact
     * matches for read.
     *
     * The record may not exist.  We can only return the correct location
     * for the record immediately after the last record in the tree, so do
     * a fast check now.
     */
    total = RE_NREC(h);
    if (LF_ISSET(S_APPEND)) {
        *exactp = 0;
        *recnop = recno = total + 1;
    } else {
        recno = *recnop;
        if (recno <= total)
            *exactp = 1;
        else {
            *exactp = 0;
            if (!LF_ISSET(S_PAST_EOF) || recno > total + 1) {
                (void)memp_fput(dbp->mpf, h, 0);
                (void)__BT_LPUT(dbc, lock);
                return (DB_NOTFOUND);
            }
        }
    }

    /*
     * !!!
     * Record numbers in the tree are 0-based, but the recno is
     * 1-based.  All of the calculations below have to take this
     * into account.
     */
    for (total = 0;;) {
        switch (TYPE(h)) {
        case P_LBTREE:
            recno -= total;

            /*
             * There may be logically deleted records on the page,
             * walk the page correcting for them.  The record may
             * not exist if there are enough deleted records in the
             * page.
             */
            if (recno <= (db_recno_t)NUM_ENT(h) / P_INDX)
                for (i = recno - 1;; --i) {
                    if (B_DISSET(GET_BKEYDATA(h,
                        i * P_INDX + O_INDX)->type))
                        ++recno;
                    if (i == 0)
                        break;
                }
            if (recno > (db_recno_t)NUM_ENT(h) / P_INDX) {
                *exactp = 0;
                if (!LF_ISSET(S_PAST_EOF) || recno >
                    (db_recno_t)(NUM_ENT(h) / P_INDX + 1)) {
                    ret = DB_NOTFOUND;
                    goto err;
                }

            }

            /* Correct from 1-based to 0-based for a page offset. */
            --recno;
            BT_STK_ENTER(cp, h, recno * P_INDX, lock, ret);
            return (ret);
        case P_IBTREE:
            for (indx = 0, top = NUM_ENT(h);;) {
                bi = GET_BINTERNAL(h, indx);
                if (++indx == top || total + bi->nrecs >= recno)
                    break;
                total += bi->nrecs;
            }
            pg = bi->pgno;
            break;
        case P_LRECNO:
            recno -= total;

            /* Correct from 1-based to 0-based for a page offset. */
            --recno;
            BT_STK_ENTER(cp, h, recno, lock, ret);
            return (ret);
        case P_IRECNO:
            for (indx = 0, top = NUM_ENT(h);;) {
                ri = GET_RINTERNAL(h, indx);
                if (++indx == top || total + ri->nrecs >= recno)
                    break;
                total += ri->nrecs;
            }
            pg = ri->pgno;
            break;
        default:
            return (__db_pgfmt(dbp, h->pgno));
        }
        --indx;

        if (stack) {
            /* Return if this is the lowest page wanted. */
            if (LF_ISSET(S_PARENT) && stop == h->level) {
                BT_STK_ENTER(cp, h, indx, lock, ret);
                return (ret);
            }
            BT_STK_PUSH(cp, h, indx, lock, ret);
            if (ret != 0)
                goto err;

            if ((ret =
                __bam_lget(dbc, 0, pg, DB_LOCK_WRITE, &lock)) != 0)
                goto err;
        } else {
            /*
             * Decide if we want to return a pointer to the next
             * page in the stack.  If we do, write lock it and
             * never unlock it.
             */
            if ((LF_ISSET(S_PARENT) &&
                (u_int8_t)(stop + 1) >= (u_int8_t)(h->level - 1)) ||
                (h->level - 1) == LEAFLEVEL)
                stack = 1;

            (void)memp_fput(dbp->mpf, h, 0);

            if ((ret =
                __bam_lget(dbc, 1, pg, stack && LF_ISSET(S_WRITE) ?
                DB_LOCK_WRITE : DB_LOCK_READ, &lock)) != 0)
                goto err;
        }

        if ((ret = memp_fget(dbp->mpf, &pg, 0, &h)) != 0)
            goto err;
    }
    /* NOTREACHED */

err:    BT_STK_POP(cp);
    __bam_stkrel(dbc, 0);
    return (ret);
}

/*
 * __bam_adjust --
 *  Adjust the tree after adding or deleting a record.
 *
 * PUBLIC: int __bam_adjust __P((DBC *, int32_t));
 */
int
__bam_adjust(dbc, adjust)
    DBC *dbc;
    int32_t adjust;
{
    CURSOR *cp;
    DB *dbp;
    EPG *epg;
    PAGE *h;
    int ret;

    dbp = dbc->dbp;
    cp = dbc->internal;

    /* Update the record counts for the tree. */
    for (epg = cp->sp; epg <= cp->csp; ++epg) {
        h = epg->page;
        if (TYPE(h) == P_IBTREE || TYPE(h) == P_IRECNO) {
            if (DB_LOGGING(dbc) &&
                (ret = __bam_cadjust_log(dbp->dbenv->lg_info,
                dbc->txn, &LSN(h), 0, dbp->log_fileid,
                PGNO(h), &LSN(h), (u_int32_t)epg->indx,
                adjust, 1)) != 0)
                return (ret);

            if (TYPE(h) == P_IBTREE)
                GET_BINTERNAL(h, epg->indx)->nrecs += adjust;
            else
                GET_RINTERNAL(h, epg->indx)->nrecs += adjust;

            if (PGNO(h) == PGNO_ROOT)
                RE_NREC_ADJ(h, adjust);

            if ((ret = memp_fset(dbp->mpf, h, DB_MPOOL_DIRTY)) != 0)
                return (ret);
        }
    }
    return (0);
}

/*
 * __bam_nrecs --
 *  Return the number of records in the tree.
 *
 * PUBLIC: int __bam_nrecs __P((DBC *, db_recno_t *));
 */
int
__bam_nrecs(dbc, rep)
    DBC *dbc;
    db_recno_t *rep;
{
    DB *dbp;
    DB_LOCK lock;
    PAGE *h;
    db_pgno_t pgno;
    int ret;

    dbp = dbc->dbp;

    pgno = PGNO_ROOT;
    if ((ret = __bam_lget(dbc, 0, pgno, DB_LOCK_READ, &lock)) != 0)
        return (ret);
    if ((ret = memp_fget(dbp->mpf, &pgno, 0, &h)) != 0)
        return (ret);

    *rep = RE_NREC(h);

    (void)memp_fput(dbp->mpf, h, 0);
    (void)__BT_TLPUT(dbc, lock);

    return (0);
}

/*
 * __bam_total --
 *  Return the number of records below a page.
 *
 * PUBLIC: db_recno_t __bam_total __P((PAGE *));
 */
db_recno_t
__bam_total(h)
    PAGE *h;
{
    db_recno_t nrecs;
    db_indx_t indx, top;

    nrecs = 0;
    top = NUM_ENT(h);

    switch (TYPE(h)) {
    case P_LBTREE:
        /* Check for logically deleted records. */
        for (indx = 0; indx < top; indx += P_INDX)
            if (!B_DISSET(GET_BKEYDATA(h, indx + O_INDX)->type))
                ++nrecs;
        break;
    case P_IBTREE:
        for (indx = 0; indx < top; indx += O_INDX)
            nrecs += GET_BINTERNAL(h, indx)->nrecs;
        break;
    case P_LRECNO:
        nrecs = NUM_ENT(h);
        break;
    case P_IRECNO:
        for (indx = 0; indx < top; indx += O_INDX)
            nrecs += GET_RINTERNAL(h, indx)->nrecs;
        break;
    }

    return (nrecs);
}